Motor vehicle wheels can be releasably fixed on the main shaft of a motor-driven wheel balancing machine for carrying out a wheel balancing operation, by the use of centering and clamping means. Reference may be made in this respect to the company prospectus from Hofmann Werkstatt-Technik GmbH, Pfungstadt, Germany, `Zentrier- und Spannmittel` `Centering and clamping means`!, imprint 9402192 02.96. When dealing with wheels which are centered at a central hole therein, the wheel is clamped in position on the balancing machine shaft by means of a central centering arrangement. In that situation, the centering effect is afforded by way of one or more centering cone portions, cone rings or special centering rings. When dealing with wheels which are centered at the bolt or stud holes on the other hand, centering bolts or pins of a conical configuration are pressed into the bolt or stud holes in the motor vehicle wheel so that the co-operation between the centering pins and the holes in the wheel produces the centering and clamping effect. A centering action can also be effected by way of the central hole in the motor vehicle wheel, in combination with centering at the bolt or stud holes. The wheel is clamped fast in position on the shaft of the wheel balancing machine by means of a clamping or pressure nut which is in screwthreaded engagement with the shaft of the machine. The nut can be in the form of a butterfly-type nut or can be in the general shape of a hand wheel or may be of some other similar hand-operable configuration so that the nut can be rotated with respect to the stationary shaft by manual rotation, whereby the resulting axial movement of the nut in relation to the shaft causes the centering cone configurations to come into action to provide for central hole centering and/or stud hole centering. To release the wheel the nut is rotated by hand in the opposite direction.
DE 42 00 380 C2 discloses effecting central hole centering of a motor vehicle wheel on the main shaft of a wheel balancing machine by means of a nut which is driven by the motor of the machine, being mounted rotatably on the main shaft, and by way of a pull bar which is passed through the main shaft and with which the nut is in screwthreaded engagement.